The following generally relates to a power starting circuit and, more particularly, to a power starting circuit for controlling a DC power supply.
As shown in FIG. 1, a currently known power starting circuit used in a hand-held power tool comprises: a switch SW11 having a first position end electrically connected to the positive pole of a DC power DC10 (the DC power DC10 is a battery pack) and a second position end electrically connected to a diode D11, a resistor R13 and a transistor Q11 respectively. The diode D11 and the resistor R13 are electrically connected to a resistor R11, a resistor R12, a transistor Q12 and a resistor R14 to form a switching circuit 100 for controlling the conducting state of an output end 11. When the switch SW1 is turned off, if the voltage of the battery pack 10 is higher than the break-over voltage of the diode D11, the transistor Q12, Q11 are on, and the circuit is started; if the voltage of the battery pack 10 is lower than the break-over voltage of the diode D11, the transistor Q12, Q11 are off, and the power supply is stopped to prevent the over discharge of the battery, wherein the break-over voltage of the diode D11 is close to the over discharge protection voltage of the battery pack 10. In the operation process, the currently known starting circuit can achieve an over discharge protection function of the battery, but it can not achieve a power saving function by automatically turned-off when the power of the battery is sufficient but not be used.